Process for Producing a Sintered Lithium Disilicate Glass Ceramic Dental Restoration and Kit of Parts

Abstract

The present invention is directed to a process for producing a sintered lithium disilicate glass ceramic dental restoration out of a porous 3-dim article, the process comprising the step of sintering the porous 3-dim article having the shape of a dental restoration with an outer and inner surface to obtain a sintered lithium disilicate ceramic dental restoration, the sintered lithium disilicate glass ceramic dental restoration comprisingSi oxide calculated as SiO2 from 55 to 80 wt.-%,Li oxide calculated as Li2O from 7 to 16 wt.-%,Al oxide calculated as Al2O3 from 1 to 5 wt.-%, andP oxide calculated as P2O5 from 1 to 5 wt.-%,wt.-% with respect to the weight of the dental restoration, the sintering being done under reduced atmospheric pressure conditions, the reduced atmospheric pressure conditions being applied at a temperature above 600° C.The present invention is also directed to a kit of parts comprising a porous 3-dim article having the shape of a dental milling block and a respective instruction of use.

1 . A process for producing a sintered lithium disilicate glass ceramic dental restoration out of a porous 3-dim article, the process comprising the step of
 sintering the porous 3-dim article having the shape of a dental restoration with an outer and inner surface to obtain a sintered lithium disilicate ceramic dental restoration,   the sintered lithium disilicate glass ceramic dental restoration comprising
 Si oxide calculated as SiO2: from 55 to 80 wt.-%, 
 Li oxide calculated as Li2O: from 7 to 16 wt.-%, 
 Al oxide calculated as Al2O3: from 1 to 5 wt.-%, and 
 P oxide calculated as P2O5: from 1 to 5 wt.-%, 
 wt.-% with respect to the weight of the dental restoration, 
   the sintering being done under reduced atmospheric pressure conditions, the reduced atmospheric pressure conditions being applied above a temperature of 600° C.   
     
     
         2 . The process according to  the preceding claim , the process comprising the steps of
 providing a porous 3-dim article, the 3-dim article having either the shape of a dental milling block or of a dental restoration with an outer and inner surface,   for porous 3-dim articles having the shape of a milling block, machining the porous 3-dim article to obtain a machined porous 3-dim article having the shape of a dental restoration with an outer and inner surface.   
     
     
         3 . The process according to  any of the preceding claims , the sintering of the porous 3-dim article having the shape of a dental restoration being conducted without supporting the inner surface of the dental restoration during sintering. 
     
     
         4 . The process according to  any of the preceding claims , the porous 3-dim article having the shape of a dental crown, dental bridge, veneer, inlay, onlay or part thereof. 
     
     
         5 . The process according to  any of the preceding claims , the porous 3-dim article being characterized by at least one of the following features:
 Pore volume: 70 to 20%;   Density: from 0.5 to 2 g/cm3;   Flexural strength: 20 to 75 MPa according to ISO 6872.   
     
     
         6 . The process according to  any of the preceding claims , the material of the sintered lithium disilicate glass ceramic dental restoration being characterized by at least one of the following features:
 Pore volume: 0 to 2%;   Density: from 2.1 to 3 g/cm 3 ;   Flexural strength: 250 to 450 MPa according to ISO 6872.   
     
     
         7 . The process according to  any of the preceding claims , the porous 3-dim article being obtained by a process comprising an additive manufacturing technology using a glass powder, the process optionally comprising the step of coloring the porous 3-dim article by using coloring components during the additive manufacturing technology. 
     
     
         8 . The process according to  any of the preceding claims , the porous 3-dim article being obtained by a process comprising the steps of:
 providing a glass powder,   pressing the glass powder to obtain a 3-dim article,   conducting a pre-sintering step to obtain the porous 3-dim article.   
     
     
         9 . The process according to  any of the preceding claims  further comprising a coloring step, the coloring step being conducted by
 either applying a coloring solution to only parts of the outer surface of the porous 3-dim article having the shape of a dental restoration, 
 or treating the whole surface of the porous 3-dim article having the shape of a dental restoration with a coloring solution, 
 
     
     
         10 . The process according to  the preceding claim , the coloring solution comprising a solvent and coloring ions selected from V, Mn, Fe, Er, Tb, Y, Ce, Sm, Dy or combinations thereof or coloring pigments comprising any of those coloring ions or combinations thereof. 
     
     
         11 . The process according to  any of the preceding claims , the sintered lithium disilicate glass ceramic dental restoration further comprising at least one, two, three or all of the following components:
 K oxide calculated as K2O: from 0.1 to 5 wt.-%,   Zr oxide calculated as ZrO2: from 0.1 to 15 wt.-%,   Zn oxide calculated as ZnO2: from 0 to 2 wt.-%,   Ce oxide calculated as CeO2: from 0 to 2 wt.-%,   Cs oxide calculated as CsO2: from 0 to 8 wt.-%,   Coloring metal oxides calculated as MO2 or M2O3, with M being a metal ion: from 0 to 5 wt.-%.   
     
     
         12 . The process according to  any of the preceding claims , the lithium disilicate glass ceramic dental restoration not comprising ZrO2 in an amount of more than 20 wt.-%. 
     
     
         13 . The process according to  any of the preceding claims , the process not comprising at least one or all of the following steps:
 machining the sintered lithium disilicate 3-dim article,   machining an article containing lithium metasilicate as main crystalline phase,   machining an article containing lithium disilicate as main crystalline phase.   
     
     
         14 . The process for producing a sintered lithium disilicate glass ceramic dental restoration out of a porous 3-dim article according to  any of the preceding claims , the process comprising the steps of
 a) providing a porous 3-dim article, the 3-dim article having the shape of a dental milling block, the porous 3-dim article having a density from 0.5 to 2 g/cm3,   b) machining the porous 3-dim article to obtain a machined porous 3-dim article having the shape of a dental restoration with an outer and inner surface,   c) optionally coloring the porous 3-dim article having the shape of a dental restoration,   d) sintering the porous 3-dim article having the shape of a dental restoration with an outer and inner surface at reduced atmospheric pressure without supporting the inner surface of the porous 3-dim article having the shape of a dental restoration during sintering to obtain a sintered lithium disilicate ceramic dental restoration, the sintering being done under reduced atmospheric pressure conditions, the reduced atmospheric pressure conditions being applied at a temperature above 600° C.,   the sintered lithium disilicate glass ceramic dental restoration having a density from 2 to 3 g/cm3 and comprising
 Si oxide calculated as SiO2: from 55 to 80 wt.-%, 
 Li oxide calculated as Li2O: from 7 to 16 wt.-%, 
 Al oxide calculated as Al2O3: from 1 to 5 wt.-%, and 
 P oxide calculated as P2O5: from 1 to 5 wt.-%, 
   wt.-% with respect to the weight of the dental restoration.   
     
     
         15 . A kit of parts comprising
 a porous 3-dim article having the shape of a dental milling block,   an instruction of use comprising the following process steps:
 machining a porous dental restoration out of the 3-dim porous article having the shape of a dental milling block, 
 optionally coloring the porous dental restoration with a coloring solution, 
 conducting the sintering of the porous dental restoration under reduced atmospheric pressure conditions, the reduced atmospheric pressure conditions being applied at a temperature above 600° C., 
 optionally sintering the porous dental restoration without using a support structure during sintering, 
   
       the porous 3-dim article having a pore volume from 70 to 20 vol.-% and comprising:
 Si oxide calculated as SiO2: from 55 to 80 wt.-%, 
 Li oxide calculated as Li2O: from 7 to 16 wt.-%, 
 Al oxide calculated as Al2O3: from 1 to 5 wt.-%, and 
 P oxide calculated as P2O5: from 1 to 5 wt.-%, 
 
       wt.-% with respect to the weight of the porous 3-dim article.